Hi Mike sorry for coming back late to your question , i just did not revisited this thread

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So your question was how to alter the HL ? or specially the red channel !!
I had the same stuff going on with Andre`s rhino image
http://www.birdphotographers.net/for...e-Investigator see there for a detailed description of how to do that .
I think it is fairly easy to do , even if Steve told me to make stuff not too complicated for others.
You can also just make a curve adjustment layer set to multiply blend mode and play with the opacity and use a mask for the HL to avoid multiplying other than the HL.
Here is another version ( option ) to deal with it. Made the RP with this , just invented this freshly for myself

, and it works even better , well for me . The key is you have to find the enemy in your RGB channels !!!! In this case it is clearly the RED channel it is washed out in the HL and mid tones .
Just check yourself all three RGB channels in PS by clicking on them in the channels palette in PS.
What i did was as follows
Duplicate the BG layer by hitting cmd - J (on mac )
set the blend mode to luminosity for the duplicated layer to avoid color shifts.
go to channels palette and click on the red channel ( you should see now the red channel on your monitor )
select the history brush tool by hitting Y on your keyboard. in the brush submenu on top of your PS workspace set the mode to "multiply " , the opacity to 50 % and the flow to 100 % . I work with a tablet , so a bit easier brush work

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now start painting the light areas with the brush to darken them , no need to be precise .
Once finished with painting , activate all three channels by clicking on the RGB composite in the channel palette , to see the result.
In case you have painted over other parts than the HL and to avoid seeing any brush strokes you can (or should) add a luminance layer mask to the duplicated layer.
Mike this is just one way to do so , for me it gives better results than the method by altering all channels with multiply method , because you are multiplying the green and the blue channel too, even if not necessary because they have enough detail in the HL .
For my RP i did exact what i described above , plus i duplicated the edited layer to make the effect stronger and levels adjustment layer for final touch up .
WDYT ? again it sounds complicated but its not , even if Steve will say so , we all have our ways to deal with it .
Cheers Andreas